Cooking unit parameter measurement (such as temperature measurement) is a difficult environment. For example, significant heat is present, there are sanitary requirements, and there are important safety demands. Reliable, accurate, and convenient operation is needed. Wired probes exist, but they are not convenient; the cables can be damaged or cut. Wireless probe systems can be complex, expensive, and unreliable. The transmit/receive frequencies employed interact with the metals of appliances to make reliable measurement very difficult. Where antenna signal strength patterns are not smooth, but notched, the link budget for probes can be too restrictive for reliable, accurate, operation. A probe placed in a low signal strength area proximate an appliance may fail to provide any signal. Considerations include power flux density, field strength, phase, polarization, and near-field effects. Missing probe signals can produce erroneous measurement values, leading to poor cooking results. Poor cooking, such as undercooking, can lead to serious illness.
Antennas, the ground plane environment, and materials must all be considered to produce results acceptable for wireless operation. The ground plane of the antenna plays a significant role in its operation. For example, if the ground plane is much larger than λ/2, radiation patterns will become increasingly multilobed. Alternatively, if the ground plane is significantly smaller than λ/2, tuning becomes increasingly difficult, and overall performance degrades. Additionally, ground surface waves can produce spurious radiation, or couple energy at discontinuities, leading to distortions in the main pattern, or unwanted loss of power.
What is needed is an antenna device and wireless transmit/receive system for communication between at least one wireless sensor and a culinary appliance to monitor the cooking process including temperature of food that provides uniform signal strength and gain performance in the near-field regions occupied by the sensor(s).